Turbulent although it has been for more than two months already, Ukraine's political conflict may now have reached a climactic crisis. This week has been marked by a series of significant weakenings of the position of President Viktor Yanukovych: first, by the removal of his hardline prime minister and long-term ally, Mykola Azarov; second, by the Ukrainian parliament's repeal, amid mounting demonstrations in Kiev, of the draconian anti-protest laws brought in two weeks ago; and, third, by the parliamentary amnesty for arrested protesters – which Mr Yanukovych has not yet signed into law.

Now the president has announced that he is taking sick leave. There may be nothing more to this news than meets the eye – although in view of the sinister illness suffered by Mr Yanukovych's predecessor and rival Viktor Yushchenko in 2004 that could be a naive view. Mr Yanukovych's defiant message on his presidential website on Thursday continued to berate the opposition and to insist that his government is intent on solving the crisis. But his step back from the frontline at such a confrontational time inevitably increases speculation that a decisive power struggle is under way and that Mr Yanukovych is closer than ever to being toppled.

Whatever the outcome, Mr Yanukovych cannot possibly succeed in reconstructing the position of power that he has maintained in Ukraine since his election in 2010. Things have gone too far for that and nor should he be permitted to do so. Mr Yanukovych presides, increasingly shakily, over a country that has been bankrupted to a quite tragic extent by a combination of his own corrupt kleptocratic circle, by the billionaire oligarchs who until now have supported him (but who may be about to side with an alternative), and by the persistent interference, including this week's threat to withhold part of the loans it offered in December, of Vladimir Putin's Russia. Mr Putin, who sees Ukraine in essentially proprietorial terms, has a lot at stake. As an authoritarian – and unlike the cautious European Union – he also has the will and means to defend it .

Whether Mr Yanukovych has run out of road or not, a tough question faces Ukraine and its neighbours. Is there a stable political process that can allow Ukrainians to make a free choice about their own government and national direction without further internal disorder and without outside – which in practice largely means Russian – interference? It is a big ask, and none of the steps will be easy. Internal Ukrainian politics are more complex and fissiparous than the much-cited pro-Russian or pro-western divide implies. But a path must be agreed towards early elections. And the EU, not just Russia, must remain engaged with and open to Ukraine's many needs.